The deployment of heterogeneous networks (Hetnets), which are mixed deployments of high power NodeBs (macro node) and low power nodes (LPNs), aims at increasing network capacity and coverage. The difference in transmit power between the macro node and the LPN causes different coverage areas for the UL and the DL.
Considering a soft handover region between a macro and an LPN, the macro node, being the more dominant node, is more likely to be the serving node. However, the signal received at the LPN can be much stronger than the signal received at the macro node. Considering the received signal to noise ratio (SNR) of the pilot channel in the uplink (UL), since both the macro node and the LPN can control the transmit power level of the user equipment (UE), the transmit power of the UE is largely driven by the LPN. As a consequence, the high speed-dedicated physical control channel (HS-DPCCH) that carries the hybrid automatic repeat request acknowledgement (HARQ-ACK) and channel quality indicator (CQI) may not be reliably decoded at the serving macro node. In this scenario, unreliable HARQ-ACK decoding, especially high ACK to discontinuous transmission (DTX) error, causes unnecessary retransmissions and degrades the downlink (DL) throughput performance.